WebGL and Screen DPI

Hey everyone,

I would like to know if there is a way to get the good Screen DPI in WebGL because it always return 0.

To extend the question, how would you use the canvas scaler for WebGL to make the UI look good on every screen size and resolution ?

Thank you very much !

 

I have this problem too. And i don't know how i can determine screen dpi without Screen.dpi.

 

I'm having trouble with this, too. Did you ever find a solution?

 

Soo I guess there's no workaround?

 

If you're just looking to support Retina builds, this worked perfectly for me: https://www.assetstore.unity3d.com/en/#!/content/74306

If you really need to know the exact DPI, you can create a Javascript bridge to the Window.devicePixelRatio via a Unity WebGL plugin.

 

Thanks for the tip, I'll look into that!

 

UP. Screen.dpi return 0 in webGL

 

Did you guys find any solution to get Screen dpi in webGL? I'm trying to make webGL work with windows screen scaling. It does not work as I expected it to work. Icons and texts are very blurry etc... I tried each of canvas scaler settings and it doesnt work. Desktop builds are working as expected.

The link provided leads to main asset store page... Thanks for any help

 

I'm currently using 2019.3.3 and Screen.Dpi always reports 0 in my WebGL builds.

Is this a regression? Has this ever worked?

 

Same problem as @jeffweber Using 2019.3.13f1 and I get a Screen.dpi = 0 when I push to the webGL build.

 

FYI, here's the workaround mentioned by inZania:

Code (JavaScript):

1. mergeInto(LibraryManager.library, {
2.  
3.     GetDPI: function ()
4.     {
5.         return window.devicePixelRatio;
6.     },
7.  
8. });

File: WebGLDPI.jslib

Code (CSharp):

1. using System.Runtime.InteropServices;
2. using UnityEngine;
3.  
4. public class CrossPlatformScreenDPI : MonoBehaviour
5. {
6. #if UNITY_WEBGL
7.     [DllImport("__Internal")]
8.     private static extern double GetDPI();
9. #endif
10.  
11.     private float dpi = 96.0f;
12.     private bool isInitialized = false;
13.  
14.     private void Initialize()
15.     {
16. #if UNITY_WEBGL && !UNITY_EDITOR
17.         double dpiFromJavascript = GetDPI();
18.         Debug.Log("dpi from javascript: " + dpiFromJavascript);
19.         dpi = (float) dpiFromJavascript * 96.0f;
20. #else
21.         dpi = Screen.dpi;
22. #endif
23.         Debug.Log("resulting dpi: " + dpi);
24.         isInitialized = true;
25.     }
26.  
27.     public float GetScreenDPI()
28.     {
29.         if (!isInitialized)
30.         {
31.             Initialize();
32.         }
33.         return dpi;
34.     }
35. }
36.  

File: CrossPlatformScreenDPI.cs

Just attach the CrossPlatformScreenDPI component to a GO and call GetScreenDPI on it to get a correct value on all platforms, including webGL.

 

Where to put the WebGLDPI.jslib file or how to link it to WebGL please?

 

That script is partially wrong, It does work to get the devicePixelRatio from the WebGl.jslib but Screen.dpi is a different thing. Dots per inch means the amount of dots in an Inch line and this is where the Unity Scripting documentation gets weird because it says "This is the actual DPI of the screen or physical device running the application. Returns 0 if unable to determine the current DPI." but DPI is typically only important for printing. So if I run Screen.dpi I get 72 but if I run the script on WebGl I get 96 because the device pixel ratio is 1 in my case so 1 x 96 = 96.
And according to Apple my screen has PPI of 128.5

Correct me if I am wrong.